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Re: Building and tuning a narrow band 2GHz cavity filter

 

On Fri, Dec 13, 2019 at 01:36 PM, Joerg ex-DB2OO wrote:
SPF5189z
I checked the datasheet. For the amplification of the LO signal 12dB should be ok. Just reduce the adf4351 output a bit. For the amplifier after the first mixer you have to add loss from first mixer (-7 dB?) and the cavity (-5 dB?) with 12dB and make sure your second mixer can handle that. My cavity has a bit more loss so I am ok with spf5189z.
It's easy to test by inserting a 10dB attenuator after the cavity filter. If that improves the IIP3 you have too much amplification.

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Erik, PD0EK
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